USB interface apparatus and USB packet transmitting/receiving method

Abstract

A USB interface apparatus is provided in electronic equipment on a USB packet transmission side, and includes a conversion unit for converting CRC object data which is data contained in a field subjected to CRC calculation in a USB packet, based on a predetermined rule corresponding to reverse conversion of conversion to be performed on the CRC object data by destination electronic equipment; a CRC calculation unit for calculating a CRC of CRC object data obtained before conversion by the conversion unit; and a packet generation unit for generating a USB packet containing data converted by the conversion unit and the CRC calculated by the CRC calculation unit.

1 . A USB interface apparatus provided in electronic equipment on a USB packet transmission side, the USB interface apparatus comprising:
 a conversion unit for converting CRC object data which is data contained in a field subjected to CRC calculation in a USB packet, based on a predetermined rule corresponding to reverse conversion of conversion to be performed on the CRC object data by destination electronic equipment;   a CRC calculation unit for calculating a CRC of CRC object data obtained before conversion by the conversion unit; and   a packet generation unit for generating a USB packet containing data converted by the conversion unit and the CRC calculated by the CRC calculation unit.   
     
     
         2 . A USB interface apparatus provided in electronic equipment on a USB packet reception side, the USB interface apparatus comprising:
 an extraction unit for extracting CRC object data which is data contained in a field subjected to CRC calculation in a USB packet and a CRC from the USB packet;   a conversion unit for converting the CRC object data extracted by the extraction unit, based on a predetermined rule corresponding to reverse conversion of conversion performed on the CRC object data by source electronic equipment;   a CRC calculation unit for calculating a CRC of CRC object data obtained after conversion by the conversion unit; and   a comparison unit for comparing the CRC extracted by the extraction unit and the CRC calculated by the CRC calculation unit.   
     
     
         3 . The USB interface apparatus according to  claim 1 , wherein conversion by the conversion unit based on the predetermined rule is performed using predetermined data shared between the source device and the destination device. 
     
     
         4 . The USB interface apparatus according to  claim 3 , wherein the predetermined data comprises a predetermined bit string, and the predetermined rule comprises an exclusive OR operation performed on a bit-by-bit basis between the predetermined bit string and the CRC object data. 
     
     
         5 . The USB interface apparatus according to  claim 3 , wherein the predetermined data comprises a common key of a common key encryption, and the predetermined rule is encryption or decode of the CRC object data on the basis of the common key. 
     
     
         6 . The USB interface apparatus according to  claim 1 , the USB interface apparatus further comprising a storage unit for storing the predetermined data. 
     
     
         7 . The USB interface apparatus according to  claim 1 , wherein the USB packet comprises a token packet or a data packet in USB communication. 
     
     
         8 . Electronic equipment comprising the USB interface apparatus according to  claim 1 . 
     
     
         9 . A USB communication system apparatus comprising a plurality of the electronic equipment according to  claim 8 . 
     
     
         10 . A USB packet transmitting method comprising:
 converting CRC object data which is data contained in a field subjected to CRC calculation in a USB packet, based on a predetermined rule corresponding to reverse conversion to be performed on the CRC object data by destination electronic equipment;   calculating a CRC of CRC object data obtained before conversion in the conversion; and   generating and transmitting a USB packet containing data converted in the conversion and the CRC calculated in the CRC calculation.   
     
     
         11 . A USB packet receiving method comprising:
 receiving a USB packet;   extracting CRC object data which is data contained in a field subjected to CRC calculation in the received USB packet and a CRC from the USB packet;   converting the CRC object data extracted in the extraction, based on a predetermined rule corresponding to reverse conversion of conversion performed on the CRC object data by source electronic equipment;   calculating a CRC of CRC object data obtained after conversion in the conversion; and   comparing the CRC extracted in the extraction and the CRC calculated in the CRC calculation.   
     
     
         12 . A USB packet communication method comprising each step in a USB packet transmitting method comprising converting CRC object data which is data contained in a field subjected to CRC calculation in a USB packet, based on a predetermined rule corresponding to reverse conversion of conversion to be performed on the CRC object data by destination electronic equipment; calculating a CRC of CRC object data obtained before conversion in the conversion; and generating and transmitting a USB packet containing data converted in the conversion step and the CRC calculated in the CRC calculation and each step in the USB packet receiving method according to  claim 11 .